use last tomcat8 version

git-svn-id: https://svn.apache.org/repos/asf/tomcat/maven-plugin/branches/tc8.x@1628864 13f79535-47bb-0310-9956-ffa450edef68
partially revert bad commit r1628603

git-svn-id: https://svn.apache.org/repos/asf/tomcat/maven-plugin/branches/tc8.x@1628865 13f79535-47bb-0310-9956-ffa450edef68
revert use of cast method

git-svn-id: https://svn.apache.org/repos/asf/tomcat/maven-plugin/branches/tc8.x@1628866 13f79535-47bb-0310-9956-ffa450edef68